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Correlation of Rpob Mutations with Minimal Inhibitory Concentration Of fmicb-07-01947 December 1, 2016 Time: 17:16 # 1 View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Frontiers - Publisher Connector ORIGINAL RESEARCH published: 05 December 2016 doi: 10.3389/fmicb.2016.01947 Correlation of rpoB Mutations with Minimal Inhibitory Concentration of Rifampin and Rifabutin in Mycobacterium tuberculosis in an HIV/AIDS Endemic Setting, South Africa Ivy Rukasha1*, Halima M. Said1,2, Shaheed V. Omar2, Hendrik Koornhof2,3, Andries W. Dreyer2,3, Alfred Musekiwa4, Harry Moultrie5, Anwar A. Hoosen1, Gilla Kaplan6, Dorothy Fallows7 and Nazir Ismail2,8 1 Department of Medical Microbiology, Faculty of Health Sciences, University of the Free State, Bloemfontein, South Africa, Edited by: 2 Centre for Tuberculosis, National Institute for Communicable Diseases, Sandringham, South Africa, 3 Department of Miguel Cacho Teixeira, Medical Microbiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa, 4 Centre for University of Lisbon, Portugal Evidence-based Health Care, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa, 5 Medical Research Council, Respiratory and Meningeal Pathogens Research Unit, School of Pathology, University of the Reviewed by: Witwatersrand, Johannesburg, South Africa, 6 The Bill and Melinda Gates Foundation, Seattle, WA, USA, 7 Public Health Sarah-Jane Haig, Research Institute, New Jersey Medical School, The State University of New Jersey, Rutgers University, Newark, NJ, USA, University of Michigan, USA 8 Department of Medical Microbiology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa Pramod Kumar, National Centre for Disease Control, India Treatment of tuberculosis (TB) and HIV co-infections is often complicated by drug- *Correspondence: to-drug interactions between anti-mycobacterial and anti-retroviral agents. Rifabutin Ivy Rukasha [email protected]; (RFB) is an alternative to rifampin (RIF) for TB regimens and is recommended for HIV [email protected] patients concurrently receiving protease inhibitors because of reduced induction of CYP3A4. This study sought to determine the proportion of RFB susceptible isolates Specialty section: This article was submitted to among RIF-resistant strains in a high HIV prevalence setting in South Africa. In Antimicrobials, Resistance addition, the study explored the association between rpoB mutations and minimum and Chemotherapy, a section of the journal inhibitory concentrations (MIC) of RIF and RFB. A total of 189 multidrug resistant (MDR) Frontiers in Microbiology Mycobacterium tuberculosis isolates from the Centre for Tuberculosis repository were Received: 21 August 2016 analyzed. The MICs were determined using a MYCOTB Sensititre plate method and the Accepted: 21 November 2016 rpoB gene was sequenced. Of the 189 MDR isolates, 138 (73%) showed resistance Published: 05 December 2016 to both RIF and RFB, while 51 (27%) isolates were resistant to RIF but retained Citation: Rukasha I, Said HM, Omar SV, susceptibility to RFB. The S531L was the most frequent rpoB point mutation in 105/189 Koornhof H, Dreyer AW, (56%) isolates, followed by H526Y in 27/189 (14%) isolates. Resistance to both RIF Musekiwa A, Moultrie H, Hoosen AA, Kaplan G, Fallows D and Ismail N and RFB was found predominantly in association with mutations S531L (91/105, 87%), (2016) Correlation of rpoB Mutations H526Y (20/27, 74%), and H526D (15/19, 79%), while D516V (15/17, 88%), and L533P with Minimal Inhibitory Concentration (3/4, 75%) were found in RIF-resistant, RFB-susceptible isolates. This study has shown of Rifampin and Rifabutin in Mycobacterium tuberculosis in an that up to 27% of MDR-TB patients in South Africa may benefit from a treatment regimen HIV/AIDS Endemic Setting, that includes RFB. South Africa. Front. Microbiol. 7:1947. Keywords: Mycobacterium tuberculosis, rpoB, rifampicin, rifabutin, minimum inhibitory concentration, HIV/AIDS, doi: 10.3389/fmicb.2016.01947 South Africa, point mutation Frontiers in Microbiology | www.frontiersin.org 1 December 2016 | Volume 7 | Article 1947 fmicb-07-01947 December 1, 2016 Time: 17:16 # 2 Rukasha et al. Rifampin and Rifabutin MIC for M. tuberculosis INTRODUCTION concentrations (MIC) of RIF and RFB among clinical MDR-TB isolates. Tuberculosis (TB) is responsible for 25% of HIV/AIDS related mortality worldwide, with sub-Saharan Africa accounting for 79% of HIV-associated TB cases (WHO, 2015). In South Africa, MATERIALS AND METHODS 65% of TB patients are HIV-positive, and TB remains the leading cause of death among HIV-infected individuals. Treatment of TB Clinical Isolates and Ethics in the context of HIV co-infection is challenging, due to the high A total of 211 MDR-TB isolates available from the Centre for potential for drug-drug interactions in combined antimicrobial Tuberculosis (CTB) repository were included. These isolates were and anti-retroviral (ARV) chemotherapy. There is an urgent collected over the first 6 months of 2010 at the National Health need to harmonize TB and HIV treatment through development Laboratory Services (NHLS) Central TB diagnostics laboratory in of compatible ARV regimens. Moreover, multidrug-resistant Braamfontein, Johannesburg from confirmed MDR-TB cases and (MDR) TB, defined by resistance to rifampin (RIF) and isoniazid submitted for analysis to the CTB, as described (Said et al., 2016). (INH), is emerging, particularly within high burden countries, Ethics approval for this study was obtained from the Research such as South Africa (WHO, 2015). MDR-TB is associated with Ethics Committee of the Faculty of Health Sciences, University of poor treatment outcomes and greatly elevated health costs. the Free State (Ref: 230408-011). Due to its sterilizing capacity, the inclusion of RIF in TB treatment regimens is crucial for achievement of high cure rates Minimal Inhibitory Concentration coupled with low relapse rates (CDC, 2013). However, RIF is a Determination of M. tuberculosis Isolates potent inducer of CYP3A4 and other cytochrome P450 enzymes, Minimum inhibitory concentrations were determined using leading to reduced serum levels of protease inhibitors, used in a commercially available Sensititre MYCOTB plate (TREK treatment of HIV/AIDS (CDC, 2013). Rifabutin (RFB) is an Diagnostics, Cleveland, OH, USA), following the manufacturer’s alternative rifamycin, which has less impact on CYP3A4 activity instructions. The MIC test range for both RIF and RFB was from and improved pharmacokinetics compared to RIF (Regazzi et al., 0.12 to 16 mg/L. Resistance and sensitivity to RIF were defined 2014). Although the activity of RFB is comparable to that of as MIC > 1 and MIC ≤ 1 mg/L, respectively, and to RFB as RIF for treatment of drug-susceptible TB, current guidelines MIC > 0.5 and MIC ≤ 0.5 mg/L, respectively, based on laboratory recommend limited use of RFB only in drug-susceptible adult standards (CLSI, 2011). TB patients with HIV/AIDS or adults experiencing intolerance to RIF. Widespread use of RFB has also been limited by its cost and absence from most commercial susceptibility testing systems DNA Extraction, PCR, and Sanger (Horne et al., 2011). However, RFB costs have been lowered by its Sequencing addition to the WHO Essential Medicines List, while the recently All isolates were grown on Löwenstein–Jensen agar; genomic validated MYCOTB Sensititre plate method includes RFB in its DNA was extracted using the phenol-chloroform (CTAB) drug panel (Lee et al., 2014). method (van Embden et al., 1993). Six primer sets were used Resistance to both RIF and RFB is largely associated with for PCR amplification of the entire rpoB gene (Table 1). The mutations in an 81-bp RIF resistance determining region (RRDR) PCR amplification protocol consisted of a 5 min denaturation ◦ ◦ ◦ within the rpoB gene of Mycobacterium tuberculosis (Jamieson step at 95 C, followed by 35 cycles of 30 s at 95 C, 30 s at 62 C ◦ ◦ et al., 2014). Although high-level cross-resistance between the and 50 s at 72 C and a final extension step at 72 C for 2 min. two rifamycins is reported, some studies have shown RFB Following Sanger sequencing of amplicons, mutations in rpoB susceptibility in RIF-resistant strains of M. tuberculosis in were identified by alignment to H37Rv reference strain (NCBI association with specific rpoB mutations (Cavusoglu et al., 2004; Accession number AL123456; Cole, 2002) using ClustalW2 (Li Yoshida et al., 2010; Jamieson et al., 2014; ElMaraachli et al., et al., 2015). 2015). Thus, it has been argued that knowing the type of rpoB mutation may have clinical implications for guiding rifamycin- Statistical Analysis based therapeutic regimens (Sirgel et al., 2013; Berrada et al., Kruskal–Wallis tests were used to determine whether mutations 2016). were associated with differences in RIF and RFB MICs. A Dunn Studies from low HIV settings have reported that 13–26% test incorporating the Benjamini–Hochberg false discovery rate of MDR-TB isolates show sensitivity to RFB (Chen et al., correction was performed to identify pairwise differences in RFB 2012; Jo et al., 2013; Schon et al., 2013). However, there is MICs. limited information on the frequency of RFB susceptibility among MDR-TB isolates in an HIV endemic region. This study aimed to determine the proportion of MDR strains RESULTS with RFB susceptibility in Gauteng Province, South Africa. Gauteng is the economic hub of South Africa, with a Of the 211 MDR isolates in the collection, MIC and sequencing large migrant workforce, where 73% of
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